ReferenceError:项未定义nodejs

Question

我试图使用node js和express从json文件中获取数据，但使用导出定义了方法，但在我的浏览器上出现错误

不确定为什么它不起作用，我已经在控制器和Routes文件夹中定义了方法

ReferenceError: item is not defined
at exports.getCityList (C:UsersacerDocumentsEDUREKAAssignmentsAssignment 5ControllersCity.js:4:36)

这是我的控制器：

const City = require('../Models/City.json');
exports.getCityList = (req, res) => {
const result = City.map(item = item.name);
res.status(200).json({
message: "City List loaded successfully",
city: result
})

}

routes.js

const express = require('express')
var CityListController = require('../Controllers/City')
const router = express.Router();
router.get('/getCityList',CityListController.getCityList);
module.exports = router;

app.js

const express = require('express');
const bodyParser = require('body-parser');
const router = require('./Routes/routes');
const hostname = "localhost";
const port = "8055";
const app = express();
app.use(bodyParser.json());
// CORS
app.use((req, res, next) => {
res.setHeader('Access-Control-Allow-Origin', '*');
res.setHeader('Access-Control-Allow-Methods','GET,POST,PUT,PATCH,DELETE');
res.setHeader('Access-Control-Allow-Headers', 'Content-Type, Authorization');
next();
});
app.use('/', router);
app.listen(port,hostname, () => {
console.log('Server is running on http://${hostname}:${port}');
})

City.json文件如下

[
{
"_id": "1",
"name": "ShalimarBhagh, Delhi",
"city_id": "1",
"location_id": "1",
"country_name": "India"
},
{
"_id": "2",
"name": "Janpat, Delhi",
"city_id": "1",
"location_id": "2",
"country_name": "India"
}

]

谢谢。

Answer 1

这一行存在问题

const result = City.map(item = item.name);

CCD_ 1的第一个自变量是回调函数。你正在做一项任务

const result = City.map(item => item.name);